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  <title>Document</title>
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  <script>
    function isLeapYear(year) {
      var flag = '平年'  // 假设不是闰年

      if(year % 4 === 0 && year % 100 !== 0 || year % 400 === 0) {
        flag = '闰年'  // 是闰年
      }

      return flag
    }

    var result = isLeapYear(2000)

    console.log(result)


  </script>
</body>
</html>